Skin permeation and metabolism of di(2-ethylhexyl) phthalate (DEHP)

Phthalates are suspected to be endocrine disruptors. Di(2-ethylhexyl) phthalate (DEHP) is assumed to have low dermal absorption; however, previous in vitro skin permeation studies have shown large permeation differences. Our aims were to determine DEHP permeation parameters and assess extent of skin DEHP metabolism among workers highly exposed to these lipophilic, low volatile substances.     

Évaluation et choix des protocoles d’imagerie sur le système de tomographie conique de basse énergie XVI® d’Elekta

PurposeThis work proposes an evaluation of the Elekta XVI^® kilovoltage cone-beam computed tomography imaging system. The average dose delivered for each acquisition protocol proposed by default by the manufacturer was measured with several detectors and compared to theoretical dose values given by Elekta. At the same time, an evaluation of image quality for pelvic protocols correlated to dose measurements in homogeneous and heterogeneous mediums allowed to optimize the use of the XVI^® system.Materials and methodsThe dose was measured for each acquisition protocol (varying filters, FOV and collimations) with four detectors (CT pencil ion chamber, 0.3 and 0.125 cm³ cylindrical ion chambers, radiothermoluminescent dosimeters) in a CTDI phantom. The dose evaluation in a heterogeneous medium was performed in an experimental anthropomorphic phantom simulating a male pelvis. Image quality was assessed with a Catphan^® 600 phantom.ResultsThe average dose measured in a homogeneous medium was about 17 mGy and 25 mGy per acquisition for Pelvis and Prostate protocols and about 17 mGy and 1 mGy for Lung and Head protocols. The study performed with different detectors showed that doses obtained were of the same order of magnitude (± 10%) and agreed with those supplied by the manufacturer. The evaluation of image quality correlated to the average dose measured allowed to optimize the use of XVI^® acquisition protocols. Measurement results in a heterogeneous medium showed a dose decrease by a factor 1.5 for bone and by a factor 2 for titanium.ConclusionThe study showed that theoretical values proposed by the manufacturer could be used to estimate the average dose delivered to the patient by the kV-CBCT imaging system. The analysis of all the results led to the implementation of a procedure allowing to optimize and account for the dose delivered to the patient by the CBCT imaging system and to report it in the patient folder.     

急性胆囊炎腹腔镜手术时机的选择及中转开腹的影响因素分析

目的 探讨急性胆囊炎腹腔镜手术时机的选择及中转开腹的影响因素.方法 160例行腹腔镜手术的急性胆囊炎患者,按出现症状距手术时间分为四组:24 h以内手术为A组(56例)、24～48 h手术为B组(42例)、49 ～ 72 h手术为C组(40例)、72 h以后手术为D组(22例),比较各组手术时间、中转开腹、住院时间及住院费用等,并分析影响腹腔镜手术中转开腹的相关因素.结果 D组中转开腹率[ 59.09％( 13/22)]明显高于A组[19.64％( 11/56)](P＜0.01).A组手术时间最短,D组手术时间最长.D组住院时间明显长于其他各组(P＜0.05).各组住院费用比较差异无统计学意义(P＞0.05).单因素分析结果显示,白细胞计数、体温、手术时机、胆囊颈部结石嵌顿是影响中转开腹的危险因素(P＜0.05).多因素回归分析结果显示,白细胞计数和手术时机是中转开腹的独立危险因素(P＜0.05).结论 急性胆囊炎腹腔镜手术中转开腹与白细胞计数、体温、手术时机、胆囊颈部结石嵌顿等因素有关,白细胞计数和手术时机是其独立危险因素.腹腔镜手术的最佳时机为发病后72h内,并且白细胞计数＜15×1099/L.     

The Effect of Dose Grid Resolution on Dose Volume Histograms for Slender Organs at Risk during Pelvic Intensity-modulated Radiotherapy

PurposeThere are enduring uncertainties regarding the optimal dose grid resolution for use with pelvic intensity-modulated radiotherapy (IMRT) plans in which the adjacent organs at risk are slender and transect the field edge. Therefore, this study evaluated the effect of dose grid resolution on bladder wall dose-volume histogram (DVH) calculations for prostate IMRT plans.Materials and MethodsThe planning computed tomography scans and clinical plans from 15 prostate cancer patients were included in this analysis. For each study computed tomography, the entire inner and outer bladder surfaces were delineated. Nine versions of the clinical plan were created, varying interval between the dose grid calculation points uniformly in three dimensions, whereas all other plan parameters were kept constant. The dose grid increments tested were 1–10 mm. The plans were recalculated and the bladder wall DVH compared against the study benchmark (1 mm grid).ResultsAll the dose grid increments evaluated resulted in a systematic overestimation of the bladder wall volume receiving low doses and an underestimation of the volume receiving high doses. Grid increments <2.5 mm all resulted in mean volume differences less than 1 cm³ across the whole DVH. Grid increments >5.0 mm resulted in mean volume differences greater than 2 cm³. Individual patient analysis revealed that only the 1.5 mm increment resulted in maximum volume differences ≤1 cm³ for every patient across the full length of the DVH curve. Bladder wall thickness ranged from 1.7 to 4.4 mm and displayed no correlation with the magnitude of the dose grid effect.ConclusionsFor an accurate DVH calculation for bladder wall during IMRT planning for prostate cancer, a 1.5 mm dose grid increment is recommended. This finding was unaffected by a normal range in bladder wall thickness. It is suggested that the application of any new treatment planning technique or organ delineation method be accompanied with an evaluation of optimal dose grid resolution.     

High dose rate brachytherapy with customized applicators for malignant facial skin lesions

PurposeBrachytherapy is a well-known treatment in the management of skin tumors. For facial or scalp lesions, applicators have been developed to deliver non-invasive treatment. We present cases treated with customized applicators with high dose rate system.Material and methodsPatients with poor performance status treated for malignant skin lesions of the scalp or the facial skin between 2011 and 2014 were studied. Afterloading devices were chosen between Freiburg^® Flap, silicone-mold or wax applicators. The clinical target volume (CTV) was created by adding margins to lesions (10 mm to 20 mm). The dose schedules were 25 Gy in five fractions for postoperative lesions, 30 Gy in six fractions for exclusive treatments and a single session of 8 Gy could be considered for palliative treatments.ResultsIn 30 months, 11 patients received a treatment for a total of 12 lesions. The median age was 80 years. The median follow-up was 17 months and the 2-year local control rate was 91%. The mean CTV surface was 41.1 cm² with a mean thickness of 6.1 mm. We conceived three wax applicators, used our silicone-mold eight times and the Freiburg^® Flap one time. We observed only low-grade radiodermitis (grade I: 50%, grade II: 33%), and no high-grade skin toxicity.ConclusionHigh dose rate brachytherapy with customized applicators for facial skin and scalp lesions is efficient and safe. It is a good modality to treat complex lesions in patients unfit for invasive treatment.     

New radiotherapy approaches in locally advanced non-small cell lung cancer

Radiotherapy plays a major role in the treatment of patients with locally advanced non-small cell lung cancer (NSCLC), particularly since most patients are not suitable for surgery due to the extent of their disease, advanced age and multiple co-morbidities. Despite advances in local and systemic therapies local control and survival remain poor and there is a sense that a therapeutic plateau has been reached with conventional approaches. Strategies for the intensification of radiotherapy such as dose escalation have shown encouraging results in phase I–II trials, but the outcome of the phase III Radiation Therapy Oncology Group 0617 trial was surprisingly disappointing. Hyperfractionated and/or accelerated fractionating schedules have demonstrated superior survival compared to conventional fractionation at the expense of greater oesophageal toxicity. Modern radiotherapy techniques such as the integration of 4-dimensional computed tomography for planning, intensity modulated radiotherapy and image-guided radiotherapy have substantially enhanced the accuracy of the radiotherapy delivery through improved target conformality and incorporation of tumour respiratory motion. A number of studies are evaluating personalised radiation treatment including the concept of isotoxic radiotherapy and the boosting of the primary tumour based on functional imaging. Proton beam therapy is currently under investigation in locally advanced NSCLC. These approaches, either alone or in combination could potentially allow for further dose escalation and improvement of the therapeutic ratio and survival for patients with NSCLC.     

Statistics for Risk Assessment of Chemical Carcinogens∗

Risk assessment is a scientific process of evaluation of potential health risks of chemical exposures to humans from available information. It involves analysis of the relationship between exposure and health related outcomes to derive an allowable exposure level. Because of lack of human exposure data, the major source of information for studying potential health effects of chemicals on humans is generally obtained from animal dose response experiments. Animal data are often evaluated in two aspects via statistical analysis: qualitative testing and quantitative estimation. The qualitative testing is to determine if the chemical causes an adverse health effect, i.e., if there is a statistically significant difference between treated and control animals. Quantitative estimation involves fitting a dose-response model to derive an allowable exposure level for humans. This paper reviews statistical principles and procedures for qualitative and quantitative approaches to human risk assessment.     

Influence of topical steroids on intraocular pressure in patients with atopic dermatitis

Background

Topical corticosteroids (TCS) can induce adverse effects, such as skin atrophy. Although TCS can cause increases in intraocular pressure (IOP), the effects of daily TCS use on IOP have not been fully elucidated. We evaluated the clinical doses of TCS and the change in the IOP during the daily treatment of atopic dermatitis (AD).

Adherence to evidence-based statin guidelines reduces the risk of hospitalizations for acute myocardial infarction by 40%: a cohort study.

AIMS: To investigate the 'real world' effectiveness of robust statin therapy, focusing on the effect of dose and early treatment discontinuation on the risk of hospitalization for acute myocardial infarction (AMI). METHODS AND RESULTS: In the PHARMO database, including among others drug-dispensing and hospital discharge records for more than two million subjects in the Netherlands, 59,094 new users of statins in the period 1 January 1991 until 31 December 2004, >or=18 years of age were identified. In these patients, exposure to statins, both in terms of persistence and dose, was determined over the first two treatment years. To determine the risk for AMI, patients were followed from this 2-year time point until the first hospital admission for AMI, death, or end of the study period. A total of 31,557 patients (53%) discontinued statin use within 2 years; 20 883 patients (35%) were persistent users with an average equipotent dose>or=4. A 30% reduction in risk of hospitalization for AMI with persistent statin use was observed. The protective effect increased with a higher dose (20 and 40% risk reduction with an equipotent doseor=4, respectively). CONCLUSION: These results show that statins are suboptimally used in real life for having the maximum benefit in terms of preventing AMI.